Reviewer: use OIC knowledge through the API #234

Context

The reviewer is OIC's first consumer. It must stay cheap and must work exactly as today when OIC isn't configured. Depends on #228. Related: #169 (org memory) moves into OIC.

Behavior to implement

• Optional config: an OIC endpoint and token. With no endpoint, nothing changes.
• One HTTP call to the context query per review (repo, changed paths, affected entities). No extra model call. The returned claims go into the prompt the review already sends, capped in tokens, preferring active, in-scope claims.
• Claims are passed as background context with their status, scope, and validity. Per ADR 0009, an OIC claim alone is not checked evidence for a finding.
• If OIC is down or slow, the review continues without it and logs one warning.
• No imports from OIC internals.

Acceptance criteria

• A review with OIC configured shows the injected claims in its debug output and costs no extra model call.
• A review with OIC unreachable completes normally.
• Per-review token overhead from OIC context is stated in the PR.